When using manually controlled testing machines, correct any tendency for the selected rate of loading to decrease, as specimen failure is approached, by appropriate adjustment of the controls.
Is the increase in rate of stress, in megapascals per second, or newtons per square millimetre per second. Is the designated dimension of the specimen, in millimetres Is the length of the specimen, in millimetres (see Figure 2) Is the rate of increase of load, in newtons per second
NOTE The required loading rate on the testing machine is given by the formula: Apply the load without shock and increase continuously, at the selected constant rate ☑0 %, until no greater load can be sustained. Select a constant rate of loading within the range 0,04 MPa/s (N/mm² x s) to 0,06 MPa/s (N/mm² x s). Ensure that the upper platen is parallel with the lower platen, during loading.Ħ.3 Loading Ensure that the specimen remains centred when the load is first applied, either by means of a jig or by temporary supports. Carefully position packing strips and, if required, loading pieces,along the top and bottom of the plane of loading of the specimen. Clean and remove any loose grit or other extraneous material from the surface of the specimen that will be in contact with the packing strips.Ħ.2 Specimen positioning Place the test specimen centrally in the testing machine, optionally using a jig. Wipe the bearing surfaces of the jig, packing strips, loading pieces and platens. These lines shall be opposite each other in an axial plane and the extremities of the two lines shall be connected over each end of the specimen, to define clearly the plane of loading.Ħ Procedures 6.1 Specimen preparation For specimens stored in water, wipe any excess moisture from the surface of the specimen before placing in the testing machine. The specimens shall be examined and any abnormalities observed shall be reported.ĥ.2 Adjustment of test specimens Where the dimensions or shapes of test specimens do not conform to EN 12390-1, because they exceed the respective tolerances, they shall be rejected or adjusted as follows: – uneven surfaces shall be levelled by grinding – the deviation of angles shall be corrected by cutting and/or grinding.ĥ.3 Marking Unless a centring jig is used, two lines shall be marked along which to apply the load. Specimens cast in moulds shall conform to EN 12350-1 and EN 12390-2. Key 1 Steel loading piece 2 Hardboard packing stripsįigure 1 - Jig for testing cylindrical specimensĥ Test specimens 5.1 General The test specimens shall be cylindrical, conforming to EN 12390-1, but a length/diameter ratio as low as 1 shall be acceptable for cores. Hardboard packing strips shall be used only once. The European Standard EN 12390-6:2000 has the status of a British Standardġ2&23 900 kg/m³ and dimensions, width (a) = (10 ± 1) mm thickness (t) = (4 ± 1) mm and a length greater than the length of the line of contact of the test specimen. Testing hardened concrete - Part 6: Tensile splitting strength of test specimens
BS EN 12390-6:2000 Incorporating Corrigendum No.1
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